1. Field of the Invention:
The present invention relates to a fuel supply system for use with an electronic control fuel injector, the arrangement being such that an inner pipe is disposed in the interior of a fuel delivery pipe, and fuel passageways are formed for smoothing a flow of fuel.
2. Description of the Prior Art:
A fuel delivery pipe hereinafter referred to as a delivery pipe) is typically intended to distribute the fuels fed from a fuel pump (not illustrate) to injectors of cylinders respectively provided in a plurality of fuel injection passageways. In this type of delivery pipe, as illustrated in FIG. 3, the fuel is fed in from one end 1a of delivery pipe 1 and fed back from the other end 1b thereof to a fuel tank (not illustrated). It is intended to make the fuel smoothly flow through delivery pipe 1
A fuel pipe 2 connected to the fuel tank is composed of a fuel feed pipe 3 and a fuel feedback pipe 4, the ends of which are fixedly arranged in one position on the side of a vehicle 5.
One end 1a of delivery pipe 1 is connected to the end of fuel feed pipe 3 through a connecting hose 6 such as a high pressure fuel hose, whereby the fuel is led to delivery pipe 1. The other end 1b thereof is connected to the end of fuel feedback pipe 4 through a connecting hose 7 such as the high pressure fuel hose. A fuel feedback port 8 provided a the other end 1b of delivery pipe 1 is, however, positioned apart from the end of fuel feed pipe 3. Therefore, if port 8 is connected to the end of pipe 3, connecting hose 7 is long extended around delivery pipe 1, thus providing a lengthy route.
This arrangement causes intricacy about an engine 9A, particularly around delivery pipe 1, resulting in such a problem as to come in contact with other hoses. An additional problem is that if connecting hoses 6 and 7 involve the use of expensive high pressure fuel hoses, there will be an increase in cost corresponding to the redundant route. To cope with this problem, as depicted in FIG. 4, there is proposed an arrangement in which a fuel introduction port 11 and a fuel feedback port 12 are provided in close proximity to each other at any one of ends 10a of a delivery pipe 10.
Fuel introduction port 11 and fuel feedback port 12 formed in delivery pipe 10 are disposed close to each other, and similarly a fuel feed pipe 14 and a fuel fuel feedback 15 of fuel pipe 13 are positioned close to each other. Hence, even when delivery pipe 10 is connected via expensive high pressure fuel hoses 16 and 17 to fuel pipe 13, these connecting hoses may be short. As a result, the costs can be reduced.
A fuel supply system adapted to maintain a high operating performance by preventing air bubbles and fuel vapor which exist in a fuel supply pipe from intermixing with the fuel fed to a fuel injection valve is disclosed in Japanese Utility Model Laid-Open Publication No. 57770/1987, wherein the delivery pipe for the fuel injector is split into an upper casing and a lower casing to provide one united body in the vertical direction. Another fuel supply system, disclosed in Japanese Utility Model Laid-Open Publication No. 29469/1987, comprises a fuel injector valve for injecting the fuels into respective cylinders, a closed-loop fuel supply aggregative passageway connected to a fuel intake of the fuel injection valve and a closed-loop fuel feedback aggregative passageway connected to a fuel feedback port of the fuel injection valve.
Conventional delivery pipe 10 is provided, at its one end, with fuel introduction port 11 and fuel feedback port 12 disposed close to each other. The delivery pipe 10 interior is not, however, formed with a passageway for smoothing a flow of the introduced fuel. Therefore, connecting hoses 16 and 17 each leading to connecting pipe 13 are connected to fuel introduction port 11 and fuel feedback port 12 as well, as when supplying the fuel into delivery pipe 10, there arises a problem in which the fuel is hard to reach the fuel injection passageway apart form fuel introduction port 11. Where an obstacle to the fuel flow is thus caused, the fuel stagnates in delivery pipe 10. This brings about problems of causing a difference in fuel temperature and a scatter in ignition.
The delivery pipe for use with the fuel injector disclosed in Japanese Utility Model Laid-Open Publication No. 57770/1987 is intended to prevent the intermixing of air bubbles but is not adapted to obviate the foregoing technical problems inherent in the prior art. The technique disclosed in Japanese Utility Model Laid-Open Publication No. 29469/1987 is conceived as an improvement of the fuel injection valve but is incapable of smoothing the fuel flow within the delivery pipe.